Kilauea, remote sensing


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This picture was taken from the Space Shuttle using an imaging radar instrument (called a Synthetic Aperture Radar or SAR) that uses electromagnetic radiation in the microwave portion of the spectrum to measure the roughness of the surface. The different colors were created by combining information contained in three channels that are sensitive to different wavelengths. North is toward the upper left hand corner of the picture. You can just see the town of Hilo at the very top of the image in the middle. Near the center of the image, a large elongate crater can be seen that has a smaller circular crater nested within it. The larger crater is the summit crater, or caldera, of Kilauea volcano and is referred to as Kilauea caldera. The smaller feature within Kilauea caldera is called Halemaumau crater.



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Satellite views provide excellent over-views of a landscape, and here we can see some of the major features of Kilauea volcano that will form part of our "Virtual Field Trip". The base image was collected by the Landsat Thematic Mapper in 1991, at a time when there was surface activity downhill from the Pu'u O'o vent.



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Oblique view of Kilauea volcano, produced from the Landsat Thematic Mapper image shown above, merged with a digital elevation model and viewed from the east.



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This is a Digital Elevation Model (DEM) of Kilauea crater. The DEM was created from TOPSAR data, which is radar data collected from an airplane. This type of DEM rendition is referred to as shaded relief.



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This is a photograph taken from an airplane (a NASA C-130) flying over Kilauea Crater. The photograph was taken with a very high precision camera made by Zeiss specifically for acquiring aerial photographs. In this picture, the sun is shining from the southwest, just as in the shaded relief rendition of the DEM above. In order to display the airphoto so that North is up, the image has been rotated and 'warped' to fit the DEM. This type of imaging warping is called geometric correction and can be very useful for orienting several different datasets in the same way.



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This image was taken by an instrument (called a Thematic Mapper Simulator) flying on the same airplane as the aerial photographic camera. In fact, the images were taken at the same time. This image is in color, but it is not the natural color that you would see if you were looking out the window of the airplane! This is because we have created the color by combining information acquired by the instrument at three different wavelengths of the electromagnetic spectrum. In order to simulate color, we have displayed data from the short wavelength infrared (this is a wavelength longer than you can see with your eyes) in red, data from the red part of the visible spectrum in green, and data from the green part of the spectrum in blue.



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This is another image of Kilauea crater taken at the same time as the Thematic Mapper Simulator image and the airphoto. Again, it looks very different from the other images. This is because all the data acquired by this instrument (called the Thermal Infrared Multispectral Scanner, or TIMS) is in the thermal infrared part of the electromagnetic spectrum. This is well beyond the wavelengths that we can see with the human eye. This part of the spectrum is called the thermal infrared because many objects on earth radiate at temperatures that can best be seen in this part of the spectrum. This image was created by doing a lot of complicated manipulation (known as principle component stretching in order to try and distinguish between different rocks. All of the rocks in this image lavas with very similar compositions, but they were all erupted at different times. The different colored lava flows in this image indicated lava flows of different ages. Just to the east of Kilauea Crater is an oblong feature, appearing pink in this image. At the western end of this feature is a small cone called Kialuea Iki.



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Here is yet another image of Kilauea crater that again looks very different from the other images above. This image was taken by an instrument similar to the one that was flown on the space shuttle (above). The difference is that this image was taken from an airplane so that you can see more detail. The information in this image was taken in the radar region of the spectrum. Radar wavelengths are far beyond the visible part of the spectrum. Radar can be very useful because, unlike the human eye, radar can see through clouds! The different colors in this image indicate different scales of surface roughness.



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This is a photograph of Halemaumau Crater taken from an airplane. Halemaumau Crater is the smaller, circular crater at the southwest end of Kilauea Crater. It can be seen each of the five previous images. Many of the 'brighter' areas in this photograph are places where vapor plumes are depositing sulfur on the surface.



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In August 1990, the NASA aircraft radar collected these data over the Ka'u Desert, which is the upper part of the Southwest Rift Zone of Kilauea. The radar collected data at C-Band (5.6 cm), L-Band (24 cm) and P-Band (68 cm) wavelengths, which are shown here in blue, green and red, respectively. These data can be used to identify differences in the texture of the lava flows; a'a appears white as it is rough (i.e., reflects the radar energy) at all wavelengths. Pahoehoe flows appear blue, since it is only at the shortest (C-Band) wavelength that they reflect the radar energy. Areas that are dark are parts of the ash produced during the 1790 eruption of Kilauea. The vents for the December 1974 lava flows are indicated by the arrows. The radar look-direction was from the top of this image.



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This is a radar image of the Pu'u O'o lava flow field on the East Rift Zone of Kilauea volcano. The data were collected by the Space Shuttle SIR-C/X-SAR radar in October 1994. The dark patches are areas of smooth pahoehoe lava, while the green areas are rough a'a and forests. The purple areas are vegetated pahoehoe flows.



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This spectacular air photograph of the Pu'u O'o cone shows many of the lava flows that have been erupted during the 12 years of activity at this site. The big plume of smoke is coming from the active lava lake. This image was obtained on September 30th, 1994 as part of a mapping program by the U.S. Geological Survey.

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Authors: Peter Mouginis-Mark & Lori Glaze

Copyright by P. Mouginis-Mark

Curator: Lori Glaze